Prosthetic heart valves have long been used to replace diseased or defective natural heart valves. One problem with prosthetic heart valves is that they tend to ear out. For example, in a prosthetic heart valve made of biological tissues, the tissues tend to progressively deteriorate due to fatigue or degenerative lesions. Accordingly, a second operation may be required to replace the prosthetic valve with a new one.
To facilitate the replacement surgery, an artificial annulus can be attached to the natural annulus, and a prosthetic valve can be releasably attached to the artificial annulus. Assemblies of this type are shown in Possis U.S. Pat. Nos. 3,997,923 and U.S. Pat. No. RE. 31,040 and Bedard U.S. Pat. No. 4,506,394.
The concept of removably attaching a prosthetic valve to an artificial annulus is desirable. However, there are problems associated with the prior art techniques for removably attaching the prosthetic valve to the artificial annulus.
For example, the Possis patents disclose the use of screw threads for threading the prosthetic valve into an artificial annulus. This requires rotation of the prosthetic valve, and this could lead to valve damage and makes angular orientation of the valve by the surgeon more difficult. The Bedard patent discloses attaching the prosthetic valve to an artificial annulus using sutures. This suturing process takes time to carry out thereby lengthening the surgery. The Bedard patent also suggests a snap-in connection between the artificial annulus and the prosthetic valve. However, this would require the application of force which might endanger any patient having a calcified annulus. Moreover, if the prosthetic valve were made resilient to allow for such a snap-in connection, there would be a danger of distortion and damage to the valve.